SEASONAL VARIATION IN THE EFFECT OF A FIXED DOSE OF HEPARIN ON ACTIVATED CLOTTING TIME IN PATIENTS PREPARED FOR OPEN-HEART SURGERY *

We investigated the effect of an injected bolus of 5 mg kg^- heparin at one circadian stage (08:30 to 11:00) on blood coagulation during different months of the year. Activated clotting times (ACTs) were assessed before and 5 min after heparin dosing to ensure extracorporeal circulation during open-heart surgery. The ACT data of 1083 presumably day-active Turkish patients (816 men and 267 women, mostly older than 46 years) who underwent coronary bypass surgery between 08:30 and 11:00 in the years from 1994 to 1997 were analyzed for annual rhythmicity. The ACT values obtained just before and 5 min after heparinization were subjected to cosinor analysis using a 365.25-day period to assess seasonality in basal ACT level and heparin effect. A small-amplitude annual rhythm with a wintertime peak was documented in the morning ACT in the group of 1083 patients. Rhythms of similar magnitude and staging were also detected in heparin effect on ACT in the 1083 patients and in subgroups categorized by gender. Circannual rhythmicity in the heparin effect on ACT was also documented in the elderly (≥ 45 years old), but not young (18-45 years old) patients. The annual mean effect of heparin on the ACT was statistically significantly greater in younger than older patients. The relatively low-amplitude circannual rhythm in heparin effect on ACT (∼10% of the annual mean) is not viewed as being meaningful in patient preparation for bypass surgery for the 5 mg kg^-1 level of heparin dosing. (Chronobiology International, 18(5), 865-873, 2001)     

Interleukin-12 increases bispecific-antibody-mediated natural killer cell cytotoxicity against human tumors

 The combination of CD16/CD30 bispecific monoclonal antibodies (bi-mAb) and unstimulated human resting natural killer (NK) cells can cure about 50% of mice with severe combined immunodeficiency (SCID) bearing subcutaneously growing established Hodgkin’s lymphoma. As interleukin-2 (IL-2) and IL-12 have been shown to increase NK cell activity, we tested the capacity of these cytokines to increase bi-mAb-mediated NK cell cytotoxicity against two types of human tumors (Hodgkin’s disease and colorectal carcinoma). Unstimulated NK cells needed a three- to five-times higher antibody concentration than cytokine-stimulated NK cells to exert similar levels of bi-mAb-mediated cytotoxicity. The augmented tumor cell lysis was achieved with IL-12 at considerably lower concentrations than with IL-2 and was associated with a significantly increased bi-mAb-mediated intracellular Ca²⁺ mobilization. The efficiency of IL-12 in this setting together with its low toxicity make it the ideal candidate for a combination therapy with NK-cell-activating bi-mAb in human tumors that are resistant to standard treatment. Received: 26 July 1995 / Accepted: 16 November 1995     

Predicting the impact of mutations on the specific activity of Bacillus thermocatenulatus lipase using a combined approach of docking and molecular dynamics

Lipases are important biocatalysts owing to their ability to catalyze diverse reactions with exceptional substrate specificities. A combined docking and molecular dynamics (MD) approach was applied to study the chain‐length selectivity of Bacillus thermocatenulatus lipase (BTL2) towards its natural substrates (triacylglycerols). A scoring function including electrostatic, van der Waals (vdW) and desolvation energies along with conformational entropy was developed to predict the impact of mutation. The native BTL2 and its 6 mutants (F17A, V175A, V175F, D176F, T178V and I320F) were experimentally analyzed to determine their specific activities towards tributyrin (C4) or tricaprylin (C8), which were used to test our approach. Our scoring methodology predicted the chain‐length selectivity of BTL2 with 85.7% (6/7) accuracy with a positive correlation between the calculated scores and the experimental activity values (r = 0.82, p = 0.0004). Additionally, the impact of mutation on activity was predicted with 75% (9/12) accuracy. The described study represents a fast and reliable approach to accurately predict the effect of mutations on the activity and selectivity of lipases and also of other enzymes. Copyright © 2016 John Wiley & Sons, Ltd.     

Ultrastructure of islet microcirculation, pericytes and the islet exocrine interface in the HIP rat model of diabetes

CONTEXT: The transgenic human islet amyloid polypeptide (HIP) rat model of type 2 diabetes mellitus (T2DM) parallels the functional and structural changes in human islets with T2DM. OBJECTIVE: The transmission electron microscope (TEM) was utilized to observe the ultrastructural changes in islet microcirculation. METHODS: Pancreatic tissue from male Sprague Dawley rats (2, 4, 8, 14 months) were used as controls (SDC) and compared to the 2-, 4-, 8- and 14-month-old HIP rat models. RESULTS: The 2-month-old HIP model demonstrated no islet or microcirculation remodeling changes when compared to the SDC models. The 4-month-old HIP model demonstrated significant pericapillary amyloid deposition and diminution of pericyte foot processes as compared to the SDC models. The 8-month-old model demonstrated extensive islet amyloid deposition associated with pericyte and beta-cell apoptosis when compared with SDC. The 14-month-old HIP model demonstrated a marked reduction of beta-cells and intra-islet capillaries with near complete replacement of islets by amyloidoses. Increased cellularity in the region of the islet exocrine interface was noted in the 4- to 14-month-old HIP models as compared to SDC. In contrast to intra-islet capillary rarefaction there was noticeable angiogenesis in the islet exocrine interface. Pericytes seemed to be closely associated with collagenosis, intra-islet adipogenesis and angiogenesis in the islet exocrine interface. CONCLUSION: The above novel findings regarding the microcirculation and pericytes could assist researchers and clinicians in a better morphological understanding of T2DM and lead to new strategies for prevention and treatment of T2DM.     

Novel Hydrophobins from <Emphasis Type="Italic">Trichoderma</Emphasis> Define a New Hydrophobin Subclass: Protein Properties,Evolution, Regulation and Processing

Hydrophobins are small proteins, characterised by the presence of eight positionally conserved cysteine residues, and are present in all filamentous asco- and basidiomycetes. They are found on the outer surfaces of cell walls of hyphae and conidia, where they mediate interactions between the fungus and the environment. Hydrophobins are conventionally grouped into two classes (class I and II) according to their solubility in solvents, hydropathy profiles and spacing between the conserved cysteines. Here we describe a novel set of hydrophobins from Trichoderma spp. that deviate from this classification in their hydropathy, cysteine spacing and protein surface pattern. Phylogenetic analysis shows that they form separate clades within ascomycete class I hydrophobins. Using T. atroviride as a model, the novel hydrophobins were found to be expressed under conditions of glucose limitation and to be regulated by differential splicing.